Jan. 30, 2012 -- A surprising new study suggests that for many children who wet the bed, the cause may start with their bowels and not their bladders.

Undiagnosed
constipation appeared to be a frequent contributor to bed-wetting among the children who took part in the research.

When these children were treated with laxatives or enemas, most stopped wetting the bed within a few months.

"Most of these kids did not have symptoms consistent with constipation and the parents had no clue," says researcher Steve J. Hodges, MD, an assistant professor of urology at Wake Forest Baptist Medical Center in Winston-Salem, N.C. "What these children had was stool in their rectums, and that is the problem we addressed in this study."

Bed-wetting and the Bowels

Hodges says stool left in the lower intestine, or rectum, can push against the bladder and reduce its capacity to hold urine.

He says even though it has been known for more than two decades that this might be a cause of bed-wetting, few doctors consider this when evaluating children with the condition.

Since normal constipation symptoms, such as infrequent or very hard stools, do not always predict whether a child will have stool in the rectum, Hodges and diagnostic radiologist Evelyn Anthony, MD, conducted abdominal X-rays to confirm it.

Their study included 30 children ranging in age from 5 to 15 (the average age was 9) being evaluated for bed-wetting at the Wake Forest Baptist Medical Center.

X-rays revealed that all of the children had some degree of rectal expansion caused by stool. Four out of five demonstrated stool burden consistent with constipation, despite the fact that just 1 in 10 had a history of constipation symptoms.

When the children received laxatives or enemas to treat the issue, 25 of the 30 (83%) were no longer wetting the bed within three months.

The study appears online in the journal Urology.

Hodges says he has used the approach to successfully treat close to 200 cases of bed-wetting and urinary reflux -- a condition characterized by abnormal flow of urine from the bladder back toward the kidneys.

"I haven't had to operate on a child for reflux in a very long time because when we empty their rectums the reflux resolves," he tells WebMD.

Bed-wetting Expert: More Study Needed

Bed-wetting is common prior to puberty, affecting about 15% of kids. It often runs in families, and boys are more likely to wet the bed than girls.

Hodges says children evaluated for bed-wetting or urinary reflux should undergo an abdominal X-ray or ultrasound to look for stool in the rectum before they are treated with drugs or surgery.

But pediatrician and bed-wetting expert David Adam Perlstein, MD, says more research is needed to confirm the findings. Perlstein is medical director for St. Barnabas Hospital in the Bronx, N.Y.

"This was a very small study and it is not clear if the treatment caused the children to get better or if they simply got better on their own," he says.

He adds that many parents might also be leery of subjecting their child to repeated X-rays or ultrasound exams even though the radiation doses are low.

Perlstein says he has had a lot of success using behavioral conditioning with bed-wetting alarms to treat pediatric bed-wetting. The moisture-sensing alarms are designed to awaken the child when urination starts with the goal of training them to awaken on their own without the alarm.

He most often prescribes the drug desmopressin for special situations, such as when a child is sleeping at a friend's house or goes away to camp.

And he recommends limiting liquids before bedtime and encouraging the child to go to the bathroom before bed.